Issue Type: Bug

Assume explorer.autoReveal: true

If a FileSystemProvider extension implements more than one scheme, and if a file is opened using a scheme that is not used by the root folder(s) of the workspace, then when focus is switched to that file a stat() call is issued on a folder resource that cannot possibly contain the file resource (because the scheme is different).

In some scenarios a stat() call on a root folder can be costly, meaning it is important not to do it unnecessarily.

This is not a new 1.37 issue.

I will add information about how to demonstrate the issue using a variant of fsprovider-sample, and I am also willing to supply a PR to fix it.

VS Code version: Code 1.37.0 (036a6b1, 2019-08-08T02:33:50.993Z)
OS version: Windows_NT x64 10.0.17134